[PATCH] Use BPF to distribute packet to different work thread.

[Vladimir Homutov]

On Thu, Sep 10, 2020 at 05:22:12AM +0000, Liu, Qiao wrote:
> # HG changeset patch
> # User Liu Qiao <qiao.liu at intel.com>
> # Date 1599735293 14400
> #      Thu Sep 10 06:54:53 2020 -0400
> # Node ID f79d524a2cc0093c53490f947564e42371cf944f
> # Parent  da5e3f5b16733167142b599b6af3ce9469a07d52
> Use BPF to distribute packet to different work thread.
> Use Berkeley Packet Filter to get packet queue_mapping number,
> and use this queue_mapping number to distribute the packet to
> different work thread, this will improve CPU utilization and http
> latency.
> Author: Samudrala, Sridhar <sridhar.samudrala at intel.com>

Do you have any real measurements with proper testing methodology?

Also, why not bind NIC queues to cores system-wide?

>
> diff -r da5e3f5b1673 -r f79d524a2cc0 auto/os/linux
> --- a/auto/os/linux           Wed Sep 02 23:13:36 2020 +0300
> +++ b/auto/os/linux        Thu Sep 10 06:54:53 2020 -0400
> @@ -32,6 +32,10 @@
>      have=NGX_HAVE_POSIX_FADVISE . auto/nohave
> fi
> +if [ $version -lt 263680 ]; then
> +    have=NGX_HAVE_REUSEPORT_CBPF . auto/nohave
> +fi
> +
> # epoll, EPOLLET version
>  ngx_feature="epoll"
> diff -r da5e3f5b1673 -r f79d524a2cc0 auto/unix
> --- a/auto/unix   Wed Sep 02 23:13:36 2020 +0300
> +++ b/auto/unix               Thu Sep 10 06:54:53 2020 -0400
> @@ -331,6 +331,17 @@
> ngx_feature_test="setsockopt(0, SOL_SOCKET, SO_REUSEPORT, NULL, 0)"
> . auto/feature
> +ngx_feature="SO_REUSEPORT_CBPF"
> +ngx_feature_name="NGX_HAVE_REUSEPORT_CBPF"
> +ngx_feature_run=no
> +ngx_feature_incs="#include <sys/socket.h>
> +                  #include <linux/filter.h>
> +                  #include <error.h>"
> +ngx_feature_path=
> +ngx_feature_libs=
> +ngx_feature_test="setsockopt(0, SOL_SOCKET, SO_ATTACH_REUSEPORT_CBPF, NULL, 0)"
> +. auto/feature
> +
>  ngx_feature="SO_ACCEPTFILTER"
> ngx_feature_name="NGX_HAVE_DEFERRED_ACCEPT"
> diff -r da5e3f5b1673 -r f79d524a2cc0 src/core/ngx_connection.c
> --- a/src/core/ngx_connection.c Wed Sep 02 23:13:36 2020 +0300
> +++ b/src/core/ngx_connection.c              Thu Sep 10 06:54:53 2020 -0400
> @@ -8,7 +8,10 @@
> #include <ngx_config.h>
> #include <ngx_core.h>
> #include <ngx_event.h>
> -
> +#if (NGX_HAVE_REUSEPORT_CBPF)
> +#include <linux/filter.h>
> +#include <error.h>
> +#endif
>  ngx_os_io_t  ngx_io;
> @@ -708,6 +711,35 @@
>      return NGX_OK;
> }
> +#if(NGX_HAVE_REUSEPORT)
> +#if(NGX_HAVE_REUSEPORT_CBPF)
> +#ifndef ARRAY_SIZE
> +#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
> +#endif
> +
> +static void attach_bpf(int fd, uint16_t n)
> +{
> +             struct sock_filter code[] = {
> +                            /* A = skb->queue_mapping */
> +                            { BPF_LD  | BPF_W | BPF_ABS, 0, 0, SKF_AD_OFF + SKF_AD_QUEUE },
> +                            /* A = A % n */
> +                            { BPF_ALU | BPF_MOD, 0, 0, n },
> +                            /* return A */
> +                            { BPF_RET | BPF_A, 0, 0, 0 },
> +             };
> +             struct sock_fprog p = {
> +                            .len = ARRAY_SIZE(code),
> +                            .filter = code,
> +             };
> +
> +             if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_REUSEPORT_CBPF, &p, sizeof(p)))
> +                            printf("failed to set SO_ATTACH_REUSEPORT_CBPF");
> +             else
> +                            printf("bpf prog attached to fd:%d\n", fd);
> +}
> +#endif
> +#endif
> +
>  void
> ngx_configure_listening_sockets(ngx_cycle_t *cycle)
> @@ -719,6 +751,11 @@
> #if (NGX_HAVE_DEFERRED_ACCEPT && defined SO_ACCEPTFILTER)
>      struct accept_filter_arg   af;
> #endif
> +#if (NGX_HAVE_REUSEPORT)
> +#if (NGX_HAVE_REUSEPORT_CBPF)
> +        ngx_core_conf_t* ccf ;
> +#endif
> +#endif
>      ls = cycle->listening.elts;
>      for (i = 0; i < cycle->listening.nelts; i++) {
> @@ -1011,6 +1048,16 @@
>          }
>  #endif
> +#if (NGX_HAVE_REUSEPORT)
> +#if (NGX_HAVE_REUSEPORT_CBPF)
> +    if(ls[i].reuseport)
> +    {
> +        ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx,ngx_core_module);
> +        if(ccf)
> +            attach_bpf(ls[i].fd, ccf->worker_processes);
> +    }
> +#endif
> +#endif
>      }
>      return;
>

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